1. Field of the invention
The present invention relates to machines for folding documents comprising single or multiple sheets. It applies in particular to a machine for folding automatically mail to be placed in envelopes.
2. Description of the prior art
Document folding machines are already widely used in the automatic handling of mail and newspapers. In the case of automatic mail handling they are usually of the so-called "pocket" type. In the case of automatic processing of newspapers they are generally of the so-called "knife" type.
Known pocket type folding machines comprise for the first fold three rollers and an associated trough (the "pocket") which is fitted with an adjustable stop member. First and second rollers receive between them each sheet to be folded which they insert into the pocket as far as the stop member. When the sheet is stopped by the stop member it forms a loop as the rollers continue to feed it. The loop is gripped between the second and third rollers to achieve the required folding. For a second fold these folding machines comprise two further rollers associated with the third of the previously mentioned rollers and an additional trough or pocket with a stop member.
The second fold is made by the third roller, the two additional rollers and the pocket associated with the latter, in the same way as the first fold.
The stop member in each pocket is adjusted to the required fold length. It is possible to obtain a single fold from a machine with multiple pockets by shutting off access to all but one pocket or by replacing each unnecessary pocket with a guide deflector.
Generally speaking, such pocket type folding machines operate in a very satisfactory way. However, their main disadvantage is that they can only accept multiple documents for folding simultaneously if they have the same format and a limited overall thickness, in other words if they comprise only a small number of identical single sheets. Also, adapting these folding machines to the number of folds required and to different fold lengths, which adjustments are made to the pockets, is an operation which although simple is relatively time-consuming.
Knife type folding machines essentially comprise a blade mounted to one side of and in line with a path along which documents to be folded are fed and on which each document is stopped, together with a pair of ejector rollers associated with the blade and mounted on the opposite side of this path. The blade is actuated transversely to the document to be folded when the document is stopped so that the document is then taken up by the pair of ejector rollers associated with the blade. A second fold can be achieved in a similar way on a second feed path coupled to the pair of rollers which eject documents from the first path. A second blade is mounted in line with this second path and is associated with a second pair of ejector rollers.
Such knife-type folding machines also function in a satisfactory way. They are generally employed to fold multiple documents having some significant thickness, such as newspapers for example. On the other hand, because the documents are stopped for each folding operation, the throughput remains low. These machines are also bulky. They also render each folding operation mandatory as otherwise the documents cannot be ejected.
The document FR-A-No. 2.424.354 discloses a machine for folding cloth articles such as tablecloths or sheets. The machine comprises pairs of belts, one long and the other short, for advancing and ejecting the articles, pivoting folding blades and deflector flaps associated with the blades. Each deflector flap diverts the article to be folded as it is advanced; the associated folding blade is pivoted to fold the diverted article. In this machine the feed direction of one of the belts is reversed to advance and divert the article and to eject it.
This machine is bulky. Also, its control system is complex because of this reversing of the feed direction of one of the belts during each folding operation.
An object of the present invention is to provide a new folding machine avoiding the disadvantages of the aforementioned known folding machines whilst incorporating their advantages. Specifically, the folding machine in accordance with the invention, which processes documents, can accept multiple documents to be folded simultaneously with different formats and with a greater or smaller overall thickness and can function with long fold lengths and at high speeds which are easy and quick to adjust; furthermore, it has small overall dimensions whereby it is extremely compact.